Peel, wash and cut the potatoes into pieces. Cook in boiling salted water for about 20 minutes. Quarter pumpkin, remove seeds, cut into slices and dice. Add pumpkin flesh to the potatoes after about 10 minutes.
Clean and trim the mushrooms and cut them into small pieces according to size. Wash tarragon, shake dry, pluck leaves except for something to garnish from the stems and chop.
Drain the potatoes and pumpkin. Press pumpkin and potatoes still hot through a potato press, season with salt, pepper. Knead starch directly under the potato-pumpkin mass. Form approx. 8 dumplings from the mixture.
Heat the oil in a pan and fry the mushrooms for about 10 minutes while turning. Season with salt and pepper. Deglaze with cream, bring to the boil and simmer for about 4 minutes. Season with tarragon.
In the meantime, let the dumplings simmer in boiling salt water for about 5 minutes until they float to the surface. Take them out and let them drain. Arrange dumplings and ragout on plates. Garnish with tarragon.